On Sun, 7 Jan 2024 17:16:41 +0800 Baoquan He <b...@redhat.com> wrote:
> with GCC 13.2.1 and W=1, there's compiling warning like this: > > kernel/panic.c: In function ‘__warn’: > kernel/panic.c:676:17: warning: function ‘__warn’ might be a candidate for > ‘gnu_printf’ format attribute [-Wsuggest-attribute=format] > 676 | vprintk(args->fmt, args->args); > | ^~~~~~~ > > The normal __printf(x,y) adding can't fix it. So add workaround which > disables -Wsuggest-attribute=format to mute it. > > ... > > --- a/kernel/panic.c > +++ b/kernel/panic.c > @@ -666,8 +666,13 @@ void __warn(const char *file, int line, void *caller, > unsigned taint, > pr_warn("WARNING: CPU: %d PID: %d at %pS\n", > raw_smp_processor_id(), current->pid, caller); > > +#pragma GCC diagnostic push > +#ifndef __clang__ > +#pragma GCC diagnostic ignored "-Wsuggest-attribute=format" > +#endif > if (args) > vprintk(args->fmt, args->args); > +#pragma GCC diagnostic pop > > print_modules(); __warn() clearly isn't such a candidate. I'm suspecting that gcc's implementation of this warning is pretty crude. Is it a new thing in gcc-13.2? A bit of context for gcc@gcc.gnu.org: struct warn_args { const char *fmt; va_list args; }; ... void __warn(const char *file, int line, void *caller, unsigned taint, struct pt_regs *regs, struct warn_args *args) { disable_trace_on_warning(); if (file) pr_warn("WARNING: CPU: %d PID: %d at %s:%d %pS\n", raw_smp_processor_id(), current->pid, file, line, caller); else pr_warn("WARNING: CPU: %d PID: %d at %pS\n", raw_smp_processor_id(), current->pid, caller); if (args) vprintk(args->fmt, args->args); print_modules(); if (regs) show_regs(regs); check_panic_on_warn("kernel"); if (!regs) dump_stack(); print_irqtrace_events(current); print_oops_end_marker(); trace_error_report_end(ERROR_DETECTOR_WARN, (unsigned long)caller); /* Just a warning, don't kill lockdep. */ add_taint(taint, LOCKDEP_STILL_OK); }